The condition that indicates a polluted environment is

Match List-$I$ with List-$II$.

List-$I$	List-$II$
$A$. Nitrogen oxides in air	$I$. Eutrophication
$B$. Methane in air	$II$. $pH$ of rain water becomes $5.6$
$C$. Carbon dioxide	$III$. Global warming
$D$. Phosphate fertilisers in water	$IV$. Acid rain

Choose the correct answer from the options given below:

Water pollution is caused due to

Which gas was responsible for the Bhopal gas tragedy in $1984$?

Which of the following statements are correct?
a) $F^{-}$ ion concentration above $2 \ ppm$ causes brown mottling of teeth
b) The maximum limit of nitrate in drinking water is $400 \ ppm$
c) Depletion of ozone layer leads to cataract and skin cancer
d) The irritant red haze in the traffic is due to oxides of sulphur

What are the effects of smoking habits for pregnant women?